Figure 1. Effects of pre-treatment with DEPC on serine influx in SNAT2- and SNAT5-expressing oocytes.

(A) Oocytes were pre-incubated for 10 min in MBM (pH 7.5) containing the indicated concentrations of DEPC or vehicle control, then rinsed before 0.5 mM L-[³H]serine influx was measured over 30 min in transport buffer (pH 8.0). Influx of serine in uninjected control oocytes has been subtracted from the values for SNAT2/5-expressing oocytes and results are percentages of the control value (±S.E.M. for nine to twelve oocytes) for amino acid influx. (B) Oocytes were pre-incubated for 10 min in NaCl transport buffer (pH 7.5) containing 2 mM DEPC (SNAT2), 3.5 mM DEPC (SNAT5) or vehicle control with or without 5 mM serine (Ser), followed where indicated by treatment with 50 mM hydroxylamine (HA) for 60 min. Oocytes were then rinsed in NaCl transport buffer and 0.5 mM L-[³H]serine influx was measured over 30 min. Pre-incubation of oocytes with serine alone had no significant independent effect on substrate influx. Each point represents the mean±S.E.M. for eight to eleven oocytes from one batch. Influx of serine in appropriately treated uninjected oocytes was subtracted from the values for SNAT2/5-expressing oocytes. *P<0.05 compared with the respective control value.